Bad beef will have a sheen to it, like slime coating that is iridescent in the light. And a very pungent odor! If you had to get yoru nose very close it it to smell anything, it's just fine. Go ahead and use it. BTW: aged beef is refrigerated for 30 days at least after slaughter.
High CPK levels are an indicator of a variety of muscle diseases and problems, not just Rhabdo. The 'normal' CPK levels are between 25 and 170. Over this number, and you have muscle cell damage happening. You can have high(er) CPK levels and not have Rhabdomyolysis. You can have muscle cell death happening, and never get to Rhabdomyolosis. You have to have -enough- cell death and -enough- myoglobin and other toxic dead cell byproducts to overwheml the system.
What Causes Muscle Cramps? Many things can trigger a muscle cramp. They include: Poor blood circulation in your legs; Working calf muscles too hard while exercising; Not stretching enough; Being active in hot temperatures; Muscle fatigue; Dehydration; Magnesium and/or potassium deficiency; A problem such as a spinal cord injury or pinched nerve in your neck or back; Muscle cramps can also occur as a side effect of some drugs. Medications that can cause muscle cramps include: Furosemide , hydrochlorothiazide , and other diuretics (water pills) that remove fluid from the body